Canopy temperature is a good indicator of crop water stress and can also be used for making timely irrigation scheduling decisions for center pivot and subsurface drip irrigation systems. A study was conducted in 2001 in which cotton (Gossypium hirsutum L.) canopy temperature was measured with infrared thermocouples and a thermal scanner in field plots irrigated by surface drip irrigation. Two water levels were established that included full evapotranspiration replacement (HW) and the other water level, which applied 50 % of the HW amount, was designated as (LW). The purpose of the study was to compare canopy temperature measured from a small canopy area using infrared thermocouples with that obtained from a larger area by thermal scanning. Canopy temperatures in the HW and LW cotton were measured on eight days during a 20 day period that started at first bloom and include four days during one irrigation cycle. In the HW level there were significant temperature differences between the two sensors on 25 % of the days, but the differences were only slightly greater than the measurement accuracy of the two sensors. In LW cotton, temperatures of the two sensors were significantly different on all days, probably due to the infrared thermocouples observing some soil surface through the canopy. Differences in canopy temperature measured by the two sensors averaged 0.2 °C in HW cotton and 3.2 °C in LW cotton. The largest canopy temperature differences measured during the irrigation cycle between HW and LW cotton was 6.75 °C and 9.1 °C, respectively, for the thermal scanner and infrared thermocouple. These results indicate that when canopy size is sufficient to mask the soil, background canopy temperatures measured from a small area by infrared thermocouples are comparable to those from a larger area sensed by a thermal scanner.